AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Impacts of Complete Street Retrofit on On-road Fine and Ultrafine Particles Concentrations: A Case Study in Santa Monica, California
Shi Shu, Nu Yu, YIFANG ZHU, UCLA
Abstract Number: 219 Working Group: Urban Aerosols
Abstract Abstract: The California Complete Streets Act of 2008 requires local governments to update general plans so that new construction or modification of roadways considers all transportation modes, which include but are not limited to walking, cycling, and driving. This work evaluates the effect of a complete street retrofit on Ocean Park Boulevard (hereafter referred to as “the retrofit”) in Santa Monica, California, in terms of ultrafine particle (UFP) and fine particle (PM2.5) concentrations. The retrofit, which cost 4.4 million dollar, was constructed on the Ocean Park Boulevard in Santa Monica, CA between December 2011 and February 2013. The pre-retrofit on-road air quality study had been completed in March and April of 2011 and the data have been published. This post-retrofit study replicated the experimental design in April 2013 after the construction was finished, to provide air quality data comparable to those in pre-retrofit study. The meteorological conditions were similar in these two studies. After subtracting background concentrations, UFP decreased after the retrofit by 4200 particles cm-3 while PM2.5 had no statistically significant change. The raw traffic volume was manually counted based on video footages captured during each test session. The emission-weighted traffic volume was calculated based on vehicle categorization and the pollutant-emitting capacities of each category, same as it was done in the pre-retrofit study. The emission-weighted traffic volume decreased 26% after retrofit, which may explain why UFP reductions were observed while total traffic flow remained the same. Although no causality could be reached, this study observed improved air quality on street after retrofit. Nonetheless, a full evaluation of the health impacts of the retrofit requires further information about how travel behavior, not just traffic, has changed.